Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and meta-analysis

The aim of this study is to determine the acute effects of resistance and plyometric training on sprint and change of direction (COD) performance in healthy adults and adolescents. A systematic literature search was conducted via Medline, Cinahl, Scopus and SportDiscus databases for studies that investigated: 1) healthy male, female adults, or adolescents; and 2) measured sprint or change of direction performance following resistance and plyometric exercises. Studies were excluded if: 1) resistance or plyometric exercises was not used to induce muscle damage; 2) conducted in animals, infants, elderly; 3) sprint performance and/or agility performance was not measured 24 h post muscle damaging protocol. Study appraisal was completed using the Kmet Quality Scoring for Quantitative Study tool. Forest plots were generated to quantitatively analyse data and report study statistics for statistical significance and heterogeneity. The included studies (n = 20) revealed sprint and COD performance was significantly impaired up to 72 hr following resistance and plyometric exercises; both protocols significantly increased creatine kinase (CK), delayed-onset muscle soreness (DOMS) and decreased countermovement jump (CMJ) up to 72 hr. The systematic review of 20 studies indicated that resistance and plyometric training significantly impaired sprint and COD performance up to 72 hours post-exercise. Both training protocols elevated exercise-induced muscle damage (EIMD) markers (CK, DOMS) and decreased CMJ performance within the same timeframe.


INTRODUCTION
The health benefits of physical exercise are irrefutable [1,2].However, strenuous exercise was shown to cause immediate and delayed alterations in cardiovascular function [3,4].Furthermore, strenuous exercise may also result in high levels of exercise-induced muscle damage (EIMD), particularly for untrained people [5].EIMD symptoms can occur due to unfamiliar eccentric contractions which are known to cause significant structural damage [5].The resulting structural damage is commonly measured by outcomes that encapsulate EIMD, such as creatine kinase (CK), delayed-onset muscle soreness (DOMS), and muscular contractility [6][7][8][9][10][11][12][13].Blood biomarkers, such as CK, can be used as indicators of muscle damage [14].It has been speculated that the disruption of the intermediate filaments reportedly activates Groups III and IV afferents, which cause an individual to experience DOMS [15].Despite the clear impairment in muscle function, classical studies since the 1980's focused on muscle function using mono-articular isometric or isokinetic contractions, which may not be applicable to sporting populations.
Incorporating 'multi-articular' activities as both EIMD protocols and motor performance measures in EIMD research would improve the application of findings to real-world practice in sports.

Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and metaanalysis
AUTHORS: Drew C. Harrison 1 , Kenji Doma 1 , Catherine Rush 2 , Jonathan D. Connor 1   1 James Cook University, College of Healthcare Sciences, Sports and Exercise Science, Australia 2 James Cook University, Biomedical Sciences and SportDiscus).MeSH terms and free text searches were combined.
The following free text search terms were used: (eccentric or resistance training or exercise) and ("muscle damage" or "creatine kinase" or soreness).

Selection process
Two authors (JC and DH) independently screened and processed the literature search.First, all abstracts were highlighted as either 'green' (definitively meeting the criteria), 'yellow' (possibly meeting the criteria) or 'red' (not meeting the criteria).After independent screening, the inter-rater reliability of the two reviewer's inclusions was assessed using 40% of the screened abstracts.A Weighted Kappa statistic of 0.78 revealed the inter-rater reliability was acceptable (95% confidence interval: 0.69-0.88)[36].Full text was then extracted from the selected articles and subjected to further screening for additional relevant publications in accordance with the inclusion/exclusion criteria.(5) training background; (6) EIMD protocol; (7) exercise type; (8) outcome measures; and (9) post-exercise time points of when outcome measures were collected (i.e., 24-, 48-, 72-hours after the muscle damaging protocol).Means ± standard deviations from pre-and postexercise outcome measures were extracted in preparation for the current meta-analyses.Any outcome measures reported as standard error or confidence intervals, or median quartiles were converted using appropriate methods [37].Each study was critically appraised using a modified Kmet rating scale [38].The Kmet quality ratings were classified as either excellent (1.00-0.8),good (0.79-0.60), fair (0.59-0.50), and poor (0-0.049).Additional criteria were incorporated to the original 14-point scoring system to assess methodological characteristics of each study, including: (1) adequate description of EIMD protocol (i.e., load, volume, rest); (2) sufficient detail of participants' training history; (3) participants being instructed to abstain from supplementation or recovery protocols.Studies were given a score of "2" if the specific criteria were met, a "1" if partially met and "0" if not met.Studies with non-applicable items were denoted with "n/a" and excluded from the final score.Two authors completed the critical appraisal of each study independently to establish an inter-rater reliability of the Kmet scoring procedure.

Statistical analysis
A meta-analysis was conducted using RevMan.To account for interstudy heterogeneity, forest plots were generated via a random effects model.All data points from post-exercise time points (i.e., 24-72-hours demonstrated that EIMD impaired vertical jump, isometric contractions, and isokinetic contractions, with concomitant increases in CK and DOMS for up to 48 hours after a variety of muscle-damaging protocols, including isokinetic eccentric contractions and downhill running.Whilst the meta-analyses by Doma et al [31][32][33] clearly shows that EIMD impaired muscle function for up to 48 hours, the studies included involved a variety of muscle-damaging protocols (e.g., isokinetic contractions and downhill running) and muscle performance measures (isokinetic and isometric contractions) that does not reflect real-world training practice.Silva et al [34] conducted a systematic review and meta-analysis and reported that vertical jump and sprint performance was impaired following competitive and simulated soccer matches.Whilst the use of soccer matches as a muscle-damaging protocol may replicate real-world exercise conditions, workloads may vary between positions, and the intensity is unable to be controlled due to the different team-specific tactics.
Furthermore, a meta-analysis which concentrates on exercises widely used for athletic development, such as resistance and plyometric training, which assess their acute effects on performance outcomes observed in sport, like sprint and COD, would be of value.Thus, the purpose of this systematic review and meta-analysis was to determine the acute effects of resistance and plyometric training on sprint and COD performance in healthy adults or adolescents.We hypothesise that both muscle damaging protocols will significantly impair sprint and COD performance for up to 48 hours post-exercise.

MATERIALS AND METHODS
The current systematic review was conducted in accordance with the PRISMA guidelines [35] and followed a population, intervention/ exposure, comparison, and outcome (PICO) approach.
Studies were excluded if: (1) they did not use resistance or plyometric exercises to induce muscle damage; (2) were conducted in animals, infants, elderly; (3) outcome measures were examined for chronic adaptation; (4) outcome measures were not compared 24 h post muscle damaging protocol; (5) sprint performance and/or agility performance was not measured; (6) they were published in non-English language; (7) results were published as a conference abstract, review, or case report.

Search strategy
A search of scientific literature was conducted on October 10 th , 2022, via four major electronic databases (Medline, Cinahl, Scopus

Methodological descriptions
The most frequently utilized sprint performance protocol was

Methodological quality
The Kmet scaling scores ranged from 0 to 2 quality (Table 3.).All included studies met the following criteria: appropriate objective and study design; participant characteristics and pre-exercise variables; and defined performance outcome measures.The Kmet items that were reported least included: resistance training history; control of post muscle-damaging protocol) were collected to calculate the magnitude of differences when compared to baseline values.Small, medium, and large (0.2, 0.5, 0.8) were values used to denote magnitude of change based upon the standardised mean differences (SMD).
The level of statistical significance of the repeated measures was determined from p-values (0.05).Differences in study design was controlled using separate equations to estimate effect of SMD and standard errors [39].

Systematic literature search
The scientific literature search of Medline, Cinahl, Scopus and Sport-Discus databases yielded 9232 abstracts.Duplicates were removed (n = 3565) and a total of 5667 abstracts were screened according to the inclusion criteria (Fig 1).After screening was completed, another 5647 abstracts were excluded, leaving 20 full text articles for inclusion (Table 2).

Participants
Table 1 displays participant physical characteristics, sample size and outcome distribution at baseline for the placebo (PLA) conditions for each study.There was a total of 208 participants which had a collective mean ± standard deviation for age, height, and body mass of 21.4 ± 2.6 years, 1.78 ± 0.8 m, and 75.3 ± 7.8 kg.

Sensitivity Analysis
When studies that investigated resistance untrained participants were excluded, the primary outcome measures (Sprint p = ≤ 0.01; SMD =   Sprint and COD performances are impaired up to 72-hours following plyometric and resistance training.Our findings disagree with Silva et al [34] who found that sprint and COD performances recovered faster (48-hours) after an 11v11 football match.These athletes may have experienced lower match-induced stress given the physical demands are known to be inconsistent between playing positions, which may have reduced their pooled effect estimate of EIMD.For example, Bradley et al [46] found large positional differences in high intensity running in elite football players.Therefore, based on our findings, greater recovery may be required for more structured exercise sessions involving strenuous eccentric contractions (i.e., resistance training and plyometrics) when compared to team sport matches.
In the current meta-analysis, comparing RT and plyometric exercises showed a consistent acute impairment in sprint and COD performance, despite fundamental differences between the training modalities.Eccentric contractions are a significant component of plyometric and resistance exercise that are known to exacerbate the signs and symptoms of EIMD [47].Several mechanisms may contribute to the symptom exacerbation such as increased mechanical stress, calcium homeostasis disruption and inflammation [48].The mechanical stress sustained has shown to impair excitation-contraction coupling mechanism which in turn results in a later reduction of muscle strength [15].Our meta-analysis supports these findings, demonstrating significant decreases in CMJ performance for up to 72-hours post-exercise.Sprinting and plyometric performance is performed optimally when morphological and neural components act in unison [49].However, EIMD may disrupt these components (i.e., muscle architecture, tendon properties, motor unit recruitment and synchronicity) by increasing the displacement of the muscle fibres during stretch-shortening cycle movements causing slower running actions (e.g., acceleration) involved with the respective sprinting and COD tasks, as evidenced in this meta-analysis.
The current meta-analysis suggested that resistance and plyometric exercise impaired sprint and COD performance up to 72 hours post-exercise.However, when inspecting the papers individually, several studies repor ted non-significant differences at 24 [16,17,19,[26][27][28][29], 48 [16,19,21,[27][28][29]42], and 72-ho urs [20,21,24,25,28,29] post-exercise, which may be attributed to previous training experience of the participants involved in these studies.For example, the paper by Goulart et al [27] found no significant difference in 20 m sprint time over the 48-hour period in professional, resistance trained, female soccer players.Additionally, de Oliveira et al [21] found that COD performance did not change up to 72-hours post-exercise in under 19 male football players who participated in strength training 3 days per week.This trend may be explained by the repeated bout effect phenomenon, which is known to reduce EIMD symptomology via neural, mechanical, and cellular pathways with greater familiarity to eccentric contractions [50].Thus, the detrimental effect of resistance or plyometric exercises has on sprint and COD performance appears to be attenuated in those who are previously exposed to strenuous exercises involving eccentric contractions (due to lower levels of EIMD).
Eccentric exercise is known to increase perception of DOMS and CK secretion.Both indirect muscle damage markers increase due to sarcomere trauma which activates the inflammatory response to repair intracellular damage [48].Our meta-analysis showed that DOMS and CK were significantly increased at 24, 48, and 72 hours after resistance and plyometric exercise.These findings are in line with traditional research that has employed isokinetic contractions [14,51,52], suggesting similar soreness trends between monoarticular and multiarticular exercises.However, these findings should be considered with caution as receptor types and perception of soreness vary between individuals [53], resulting in high inter-study heterogeneity which is common among DOMS and CK values in meta-analyses [31][32][33].
Nonetheless, our findings confirm that resistance and plyometric exercises are muscle-damaging exercises, and athlete discomfort should be considered when planning subsequent training sessions (particularly those involving sprint and COD exercises).
According to the critical appraisal analyses, we found several methodological concerns from previous studies that should be analyses indicated that removal of trained participants exhibited minimal impact on the overall meta-analyses.Fourth, whilst COD and sprint performance are representative of movements observed in sports, the findings from this meta-analysis may not translate to movement or sport-specific skills, such as throwing or kicking accuracy.Finally, whilst the inclusion criteria strictly included studies that utilised either plyometrics, resistance exercises or the combination as muscle-damaging protocols, the subtle differences in the type of exercises may have influenced our results.However, the sensitivity analyses showed that when studies with plyometric exercises were removed, the overall meta-analyses did not change.

CONCLUSIONS
Our systematic review and meta-analysis demonstrated a significant impairment of sprint and COD performances for 24-72-hours following resistance and plyometric exercises.Therefore, coaches should monitor each athlete's individual response to these training methods, adapting their exercise prescription and integrating appropriate time for recovery when EIMD is observed.
addressed in future research.Firstly, whilst most studies reported key training variables for the muscle-damaging protocols, such as load, repetitions, sets, rest and exercise order, some studies did not provide sufficient methodological description to replicate the muscle-damaging protocol [24,29,40,[43][44][45].Future research must clearly outline the muscle damaging protocols [30,54,55].Secondly, limited number of studies provided replicable information on participants' training history.This information is important as previous resistance training exposure can significantly reduce the level of muscle damage due to the repeated bout effect phenomenon [56].
Third, only few studies [17,[19][20][21] controlled for dietary and supplementation habits and implemented familiarisation sessions during the testing period.Future research should consider restricting foods known to reduce the signs and symptoms of EIMD [31][32][33] and incorporate familiarisation sessions to limit the learning effect.
There are limitations that exist within the current systematic review and meta-analysis which should be noted.Firstly, the I 2 values for CK and DOMS ranged between 65%-81%, indicating high inter-study heterogeneity.Secondly, articles not published in English were excluded, possibly biasing our meta-analysis from a cultural and linguistic standpoint.Thirdly, we combined studies with participants from various training backgrounds, which may have influenced the results due to the repeated bout effect.However, the sensitivity An excel spreadsheet was used to extract descriptive information involving (1) study;(2) research design (i.e., randomised, placebo control or cross-over); (3) sample size; (4) physical characteristics; 30 m sprint (4 studies), followed by 20 m sprint (3 studies), 15 m sprint (3 studies), 10 m sprint (2 studies), 40 m, 50 m, 100 m sprint with one study each.Only two studies investigated repeated sprint ability over 10 m and 35 m distances, respectively.The most common agility performance protocol was the T-test agility (5 studies), followed by the Illinois agility test (2 studies), Square test (1 study), Y-test (1 study) and M-test (1 study).The most reported biomarker of muscle damage was CK (12 studies), whilst only two studies reported myoglobin and six studies reported no blood biomarkers.CMJ was the most reported jump performance measure (14 studies) whilst only four studies assessed drop jump (DJ) performance.The most reported DOMS measure was VAS 0-10 (13 studies), other measures included 5-point Likert scale (1 study), 10-point Likert scale (1 study), Total quality recovery (2 studies), 10 cm pain scale (2 studies), Navigate pain application (1 study) and a 6-point acute recovery and stress scale (ARSS).

FIG. 2b .
FIG. 2b.Forest plot for sprint performance at 48-hours after the muscle damaging protocol

TABLE 1 .
Participant characteristics and baseline comparisons of outcome measures
factors that may bias the results (i.e., supplements, recovery interventions, familiarisation); and sample size appropriation.

TABLE 3 .
Kmet scores of all included studies FIG. 2c.Forest plot for sprint performance at 72-hours after the muscle damaging protocol